class A {
  double f(double x,double y){
	return x+y;
  }
}
class B extends A{
	double f(int x,int y){
		return x*y;
  }
}
public class ceshi5_4 {
	public static void main(String args[]){
		B b=new B();
		System.out.println(b.f(3.0,5.0));
  }
}